As we already reported a little while ago, the Ommadawn prospect targeted by OMV and partners Petoro (20%) and Neptune (20%) in PL970 was an interesting well to follow in the light of previous exploration activity nearby. Now that the well has been completed and the results announced, there are surely plenty of things to mull over for the operator and its partners.
First of all, the primary target of the well turned out dry; the Upper Cretaceous Tor Formation on top of the Ipswich salt dome was water-bearing. However, a 3-metre oil-bearing interval was encountered in the Ekofisk Fm overlying the Tor, but this succession was reported as a probable residual oil zone. If that is the case, it is possible that salt movement caused the seal to the Ekofisk accumulation to breach after initial filling.
Yet, the most interesting aspect of the well result is still to come. As we discussed in our article published when the well had just spudded, the nearby 1/3-11 and 1/3-11T2 wells drilled by Dong in 2008 proved both the Forties and slightly deeper Andrew sandstones to be oil-bearing in a more downdip position from where 1/3-13 has now been completed. The 1/3-11 parent well failed to find the Forties sandstone, but the more downdip T2 well did.
When looking at the schematic cross-section presented below, it seems likely that OMV did not expect the Forties sandstone to be present in 1/3-13, as it was missing in well 1/3-11. Yet, it was found, with a thickness of 8 metres and oil-bearing. That may have been a surprise, and it is therefore understandable that the NPD press release states that “more detailed studies will be needed to determine potential connection between the proven resources in the Forties and Andrew formations in the recently completed well and the 1/3-11 discovery.”
The second positive aspect to well 1/3-13 is the fact that oil was also found in the Andrew sandstone. Even though the thickness of the reservoir is only 3 metres, it shows that the Andrew sandstone also drapes over the Ipswich Salt dome, which can only be a good thing when it comes to allocating resources to this interval.
In summary, even though the outcome of well 1/3-13 is not as was hoped for, it will present the partnership with an interesting geoscience case study to unravel the architecture of Paleocene reservoirs overlying the Ipswich Salt dome.
HENK KOMBRINK
